CAT-354 Clinical Update

Cambridge Antibody Tech Group PLC
23 June 2005


FOR IMMEDIATE RELEASE


07.00 BST, 02.00 EST Thursday 23 June 2005

For further information contact:        Weber Shandwick Square Mile (Europe)
Cambridge Antibody Technology           Tel: [phone]
Tel: [phone]               Kevin Smith
Peter Chambre, Chief Executive Officer  Yvonne Alexander
John Aston, Chief Financial Officer     Rachel Taylor
Rowena Gardner, Director of Corporate
Communications                          BMC Communications/The Trout Group (USA)
                                        Tel: [phone]
                                        Brad Miles, ext 17 (media)
                                        Brandon Lewis, ext 15 (investors)

CAMBRIDGE ANTIBODY TECHNOLOGY ANNOUNCES DATA FROM PHASE I CLINICAL TRIAL OF 
CAT-354

Cambridge, UK - Cambridge Antibody Technology  (LSE: CAT; NASDAQ: CATG) today
announces that preliminary results of a Phase I clinical trial of CAT-354, a
human anti-IL13 monoclonal antibody being studied as a potential treatment for
severe asthma, showed CAT-354 to be well tolerated with no safety concerns
identified.

The objective of the trial, which commenced in September 2004, was to assess the
safety, tolerability and pharmacokinetics of CAT-354. It was a double-blind,
placebo-controlled, rising single dose intravenous study in 34 mild asthmatic
patients. Preliminary results showed that CAT-354 was well tolerated at all
doses and there were no identified safety concerns; pharmacokinetics were as
anticipated. The trial results will be submitted to an appropriate scientific
meeting in due course.

Based on these results, CAT is planning to start a clinical pharmacology study
in the fourth quarter of 2005. This is being planned as a repeat dose allergen
challenge study in patients with asthma.

Patrick Round, VP Development at CAT, commented: "CAT-354 is an important
product candidate for CAT and this trial was the first clinical step in its
development as a potential treatment for severe asthma. We are encouraged by
these preliminary results and are now moving forward with plans for a second
clinical trial."

- ENDS-

Notes To Editors - Cambridge Antibody Technology (CAT):

Business:
    - CAT is a leading biopharmaceutical company, committed to
      developing fully human monoclonal antibody therapeutics to treat human 
      diseases in areas of unmet medical need
    - CAT has a strong financial position and expects growing revenues from 
      HUMIRA(R). In addition, CAT has good medium term prospects from 10 further 
      CAT-derived clinical development programmes and significant opportunities 
      for growth in the longer term.
Products:
    - HUMIRA, licensed to Abbott, is the first CAT-derived antibody to be 
      approved for marketing. It was isolated and optimised in collaboration
      with Abbott and has been approved for marketing as a treatment for 
      rheumatoid arthritis in 58 countries.
    - There are six further CAT-derived antibodies licensed to partners at 
      various stages of clinical development, including ABT-874 (Abbott),
      LymphoStat-B, HGS-ETR1, HGS-ETR2 (all HGSI) and MYO-029 (Wyeth). CAT has 
      also licensed its proprietary technologies and patents to several companies,
      including: Abbott, Amgen, Chugai, Dyax, Genzyme, Human Genome Sciences, 
      Merck & Co, Micromet, Pfizer and Wyeth Research, and three antibody drug 
      candidates are in clinical development at IP licensees.
    - There is one proprietary CAT human therapeutic antibody product candidate, 
      CAT-354, in clinical development, with one further product candidate, 
      GC-1008 (with Genzyme), in pre-clinical development. 
Collaborations:
    - CAT has a broad collaboration with Genzyme for the development and 
      commercialisation of antibodies directed against TGFbeta, a family of proteins
      associated with fibrosis and scarring, and with potential application in 
      the treatment of some cancers.
    - CAT has major strategic alliance with AstraZeneca to discover and develop 
      human antibody therapeutics, principally in inflammatory disorders. This 
      provides CAT with the opportunity to build a substantial pipeline of 
      antibody therapeutics with a significant pharmaceutical partner.
    - CAT has a third co-development collaboration with Amrad.
Science:
    - CAT has an advanced proprietary technology for rapidly isolating human 
      monoclonal antibodies using Phage Display and Ribosome Display systems. 
      CAT has extensive phage antibody libraries, currently incorporating more 
      than 100 billion distinct antibodies, which form the basis for the 
      Company's strategy to develop a portfolio of antibody-based drugs.
Business Background:
    - Based near Cambridge, UK, CAT currently employs around 290 people.
    - CAT is listed on the London Stock Exchange (CAT) and on NASDAQ (CATG).
    - CAT raised £41m in its IPO in March 1997 and £93m in a secondary offering 
      in March 2000.
    - More information can be found at www.cambridgeantibody.com 
IL-13 and CAT-354:
    - IL-13 is an interleukin (protein) which has potent immunomodulatory 
      effects. It is primarily secreted by TH2 lymphocytes. It is believed to be 
      a highly relevant target molecule for asthma as a result of its potential 
      role in airways obstruction, acute exacerbations and in chronic airways 
      remodelling.
    - CAT-354 is the first CAT antibody optimised using CAT's proprietary 
      ribosome display technology to enter clinical development. 
    - CAT-354 is the latest CAT-derived antibody to enter clinical trials.

Application of the Safe Harbor of the Private Securities Litigation Reform Act
of 1995: This press release contains statements about Cambridge Antibody
Technology Group plc ("CAT") that are forward looking statements. All statements
other than statements of historical facts included in this press release may be
forward looking statements within the meaning of Section 21E of the Securities
Exchange Act of 1934. These forward looking statements are based on numerous
assumptions regarding the company's present and future business strategies and 
the environment in which the company will operate in the future. Certain factors 
that could cause the company's actual results, performance or achievements to 
differ materially from those in the forward looking statements include: market 
conditions, CAT's ability to enter into and maintain collaborative arrangements, 
success of product candidates in clinical trials, regulatory developments and 
competition. We caution investors not to place undue reliance on the forward 
looking statements contained in this press release. These statements speak only 
as of the date of this press release, and we undertake no obligation to update 
or revise the statements.



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